Local dark matter density

A precise determination of the local dark matter density and an accurate control over the corresponding uncertainties are of paramount importance for Dark Matter (DM) searches. Using very recent high-resolution numerical simulations of a Milky Way like object, we have studied the systematic uncertainties that affect the determination of the local dark matter density based on dynamical measurements in the Galaxy. In particular, extracting from the simulation with baryons the orientation of the Galactic stellar disk with respect to the DM distribution, we have studied the DM density for an observer located at $\sim$8 kpc from the Galactic center {\it on the stellar disk}, $\rho_0$. This quantity was found to be always larger than the average density in a spherical shell of same radius $\bar{\rho}_0$, which is the quantity inferred from dynamical measurements in the Galaxy, and to vary in the range $\rho_0/\bar{\rho}_0=1.01-1.41$. This implies that the actual dark matter density in the solar neighborhood is on average 21% larger than the value inferred from most dynamical measurements, and that the associated systematic errors are larger than the statistical errors recently discussed in the literature. The full paper can be found at

(copyright image O. Agertz http://www-theorie.physik.unizh.ch/~agertz)